Refrigerating apparatus



*Dezwz ALQGRQMS- 2,101,498

` REFRIGERATING4 APPARATUS Filed June 27, 1935 2 vSheets-#Sheet 1 fnl/111 lll 11 111 1 r l 1 1 l 111 111 www ATTORNEYS 'Dea 7, 1937. A o, GROQMS 2,101,498

REFRIGERATING APPARATUS v Filed June 27, 1935 2 Sheets-Sheet 2 Patented Dec. 7, 1937 PATENT OFFICE BEFRIGERATING APPARATUS Albert 0. Grooms, Dayton, Ohio, assigner to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application .lune 27, 1935, Serial No. 28,685

i Claims'.

This invention relates to refrigerating apparatus and more particularly to control means therefor.

In household refrigerators, the refrigeratlng system is not only called upon to cool the food compartment of the refrigerator, but also to freeze ice cubes and comestibles. For simplicity, a single refrigerating system is used for these dual purposes and in order to maintain proper control over the freezing function of the refrigerating system, the control of the' system has been by the evaporator temperature. Under average conditions, this is fairly satisfactory, but under adq verse conditions, such as when the outside temn perature is excessively high or abnormally low, it has been found that the food compartment either becomes too warm in the :Erst instance, or toc cold in the second instance.

It is, therefore, an object or my provide a refrigerating apparatus tv ich is con tures.

It is another object oi my invention to provide a refrigeratlng apparatus which is controlled according to the temperature of the evaporating means and the duid cooled by e evaporating means, one of which serves as 'the control for the refrigerating system and the other of which serves as a compensating control.

Further objects and advantages ci the present invention will be apparent from the following description, reference being'liad to accom panying drawings, wherein a preferred-form oi the present invention is clearly shown.

In the drawings:

Fig. 1 is a fragmentary view, partly diagrammatic. of a refrigerating apparatus embodying my invention;

Fig. 2 is a modied form of contrai means for the apparatus shown in Fig. i;

Fig. 3 is a sectional view ci the control means shown in Fig. 1; and

Fig. 4 is another modified form oi control means for the apparatus shown in Fig. l.

In my disclosure, I have shown a domestic tion of the compressor. This control means also has a second thermostatic bulb and bellows re sponsive to the temperature of the air within the food compartment. 'This thermostatic bulb is preferably located so as to either be responsive to the warmest temperature in the food compartment, or to reflect'the average air temperature within the food. compartment. This second thermostatic bulb and bellows are provided for compensating the switch so as to prevent the food compartment :from becoming too cold or too Warm. iliere are three diderent forms shown; in the one shown in Figs'. land S, the com= presser switch is prevented from closing or tendn ing to be prevented from closing *when the box temperature is low and which is 'prevented from opening or tending to be prevented from opening when the box or toad compartment temperature is high. En 2 the form is shown in which the lower evaporator temperature limit ci the control n,

means is changed according to the temperature of the air Within thefood compartment. In Fig. l, another form is shown in which the upper and; lower evaporator temperature limits are changed according to the ten'rperature o the Within the food compartment.

Referring now more particularly to 'the draw ings, there is shown a refrigerator cabinet, generalij/- designated by the. reference character 2@ having outer metal walls i2, inner metal walls 2Q, and insulating means 26 between the inner and outer metal Walls. The inner metal Walls surround a food or cold storage compartment containing a cooling unit or refrigerant evapon rating means 30 having ice freezing chambers 32 and 3i containing shelves 36 and 3S for receiving ice trays. IIfile evaporating means 3S is supplied with liquid refrigerant by a compressor 4B driven by an electric motor 42 for compressing the rerigerant and for forwarding the compressed refrlgerant to a condenser 44 where the compressed refrigerant is liquefied and collected in a receiver it. The 'liquid refrigerant is forwarded to the evaporating means through' a supply conduit 4G under the control of a suitable form oi' valve or restrictor 50 such as an expansion valve or high side float. From the evaporating means, the liquid refrigerant is returned to the compressor through the return conduit 52.

It has become rather popular to mount the control means of the refrigerating lsystem upon the evaporator. This is convenient from several standpoints, since .the thermostatic bulb must be connected with the evaporating means in some suitable way and since when so located, the con- Vasl trol means requires no connections other than the electrical conductors extending through the walls of the refrigerator cabinet. I have, therefore, shown my control means. generally desig- -nated by the reference character 64, connected 4by the electrical conductors 56 through the walls of the cabinet to the electric circuit of the el'ec' tric'motor 42. This control means 64 is connected by a small tube 58 to a thermostatic bulb 60 mounted in direct heat exchange relation with a side wall portion of the evaporating means 80 and is connected by a similar, but longer tube 62,to a thermostatic bulb 64 mounted upon the side wall of thev inner metal walls 24. and in heat exchange relation therewith so this bulb may.

receive 'an indication of increased food compartment temperatures as early as possible.

Referringnow more particularly to Fig..3 for a more complete disclosure of the control means 54, there is shown a casing 66 in which the tube 58 and the thermost'atic bulb 60 are connected to the fixed end of a metal bellows 68 which is mounted upon a platform 10 extending from a side wall of the casing 66. The free end o! the bellows 68 is connected to a primary lever 12 provided with a pivot' 14 upon the wall of the casing and provided with a-pair of notches 16 at its opposite end which receive the knife edges formed upon the adjacent ends of the secondary lever 18. .This secondary lever 18 is connected by a tension toggle spring 80 to a contact carrying lever 82 pivoted upon the pivot pin 84 to an `insulated portion 86 of the wall of the control casing 66. This lever 82 is provided. with a contact 88 which cooperates with a contact 90 mounted upon an insulated portion 92 of the casing 66. The contact 90 is connected to one ofthe conductors oi the control circuit 56, while 'the pivot pin'84 is connected-to another ofthe conductors of the circuit-56. The movement o i A the lever 82 is controlled in one direction by the Vcontact 80 and in the opposite direction by a l set screw M Which may be moved to change the range of movement of the lever 82 andin that way to change the diierential of the switch. The range vcontrol of the switch is provided by a ten-v sion spring 96 connected at one end to a lever 12 and at its opposite end through a connector 98 to an adjusting screw |00 which isprovided for adjusting or changing the range of the switch as desired.

The portion of the control means thus far described provides, a control which controls the operation of' the refrigerating system and the temperature of the evaporating means directly according to the temperature of the evaporating means. Thereforaif an abnormal food load is placed within the refrigerati'ng system, or warm ice trays are placed `within the cooling unit or if the temperature without the cabinet changes mounted upon the wall of the casing 86 which acts upon a lever |04 pivoted at |06 to a projection from the wall of the casing. The expansion of the bellows |02 is controlled by the' ccm- .These two nuts ||4 are spaced far enough apart and a set'screw ||0 is normally so adjusted that when the temperature of the air within the food compartment' is within a desirable range, such asbetween 42 and 45 F., or possibly between 40 and 50F., these nuts ||4'and ||6 are entirely out of the path oi the primary lever 12 andunder such conditions, the refrigerating system is con'- trolled altogether according to the evaporator temperature. Thus, should the temperature within the food compartment 28 become` too cold, such as below 40 or 42 F., the bellows |02 will contract and move the nut ||4 into the pathof the primary lever 12 so as to prevent or tend to prevent the primary lever from being moved upwardly a suicientdistance 'to trip the toggle mechanism to circuit closing position. Thus, the operation ot the electric motor and the compressor would be stopped if they were in operation or they would be prevented from starting .when not in operation under such conditions. I! the temperature of the air in the food compartment should become too warm, the bellows |02 will expand and move the Anut ||6 into the path of the primary lever 12 so as to prevent or tend to prevent the primary lever 12 from moving a sufllcient distance in the downward direction to cause the toggle mechanism to trip the contacts to open circuit position. Thus, when the temperature within the food compartment rises above 45 or 50 F., the electric motor and the compressor will either be started or made to continue operation. While I have described this apparatus as particularly applied to a vdomestic refrigerator cabinet, it is obvious that the system of .control may be applied wherever an evaporator is used to cool a fluid. i

In Fig. 4,1 have shown a modified form of control means which at ilrst glance bears a close re tact 288 cooperating with a contact 280 in a manner altogether similar to the form shown in Fig.

, 3. A set screw 284 is similarly provided for the differential adjustment and a tension springl 29.6 and an adjusting screw 300 are similarly provided for the range adjustment. The compensating control in a similar way includes a thermostatic which operates a lever 304.

Thus far, the compensating mechanism is similar tothat shown in Fig. 3. However, instead of providing a rod and nuts which are moved into .the path oi the primary lever. the lever 804 is 4connecteclby an adjusting screw M8, a connector bullo 288, a tube 282, a bellows 302 and a compression spring 308 and an adjusting screw 8| 0 32| and a tension spring $22 with the primary lever 212. In this form of control, the bellows 262 tends to operate the switch mechanism according to the temperature of the evaporating means as interpreted by the thermostatic bulb 260, but the bellows 302 through the lever 3M and the spring 322 imposes a somewhat weaker force upon the switch mechanism according to the temperature of the air Within the food compartment as interpreted by the thermostatic bulb 264. Thus. when the temperature of the food compartment is too cold, the bellows 302 contracts to reduce the tension upon the spring 322 so as to increase the eective load upon the bellows 268 in order to cause the switch to be moved to open position at a slightly higher low temperature limit of the switch mechanism and to close at a slightly higher evaporator temperature so as to prevent the food compartment from becoming too cold. When the food compartment is too warm, the reverse occurs and the bellows 302 expands to increase the tension of the spring 3 22 so as to reduce the eective load upon the bellows 268 and make it easier to move the switch mechanism to closed position. This, of course, will tend to lower the upper andv lower temperature limits of the evaporator so as to provide increased refrigeration to prevent the food compartment i'rom becoming too warm.

In Fig. 2, the switch mechanism similarly includes a bellows 388 which expands according to the evaporator temperature and which operates a primary lever 312, a secondary lever 318, a toggle spring Isl, and a switch contact lever 282 carrying a switch contact l". In a similar way, it is also provided with a differential adjusting screw I and a range spring 298 and a range ad? Justing screw 4". This switch or control mechanism however, diflers from the other two in its compensating mechanism. For its compensating mechanism, this control shown in Fig. 2 is provided with a charged metal bellowsl having its upper end fixed by a vbracket 422 to a wall of the Y control housing and having its lower movable end acting upon the arm t of a bell crank lever which has a second arm |32 carrying a switch contact I which is adapted to be engaged by the contact Ill of the switch mechanism. This I bell crank lever, having the arms t and |32, is pivoted upon a pivot pin "I to a bracket held by aninsulated portion l of the wall of the switch housing. A tension spring l is provided -ior holding the arm l in contact with the lower 'end ofthe charged bellows |20 and for imposing asiiiilclent load upon the bellows III. This bellows 420 is exposed to the air within the food compartment and changes the position oi the contact 434 so as to raise or lower the lower temperature limit, thatV is the cut-out temperature. of the switch mechanism according to the iall or rise in temperature of the air within the lood compartment 28 so as to prevent the lood compartment from becoming too c old or too warm. Thus, this Aform also provides eective compensation.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope o! the claims which follow.

What is claimed is as follows:

l. Reirigerating apparatus including an enclosure containing a fluid to be kept cool, a system associated with said enclosure comprising a cooling element in -heat relation with the rluid in the enclosure and a cooling medium circulating unit outside the enclosure, means dependent solely upon the temperature of the cooling element and providing the main control for normally controlling the operation of said circulating unit, and means disposed within said enclosure out of intimate thermal contact with said cooling element and acting directly upon said Vtemperature dependent main control means for thermal contact with said evaporating meansA and acting directly upon said temperature dependent main control means for regulating same in response to the temperature of ambient air in said compartment. n

3. Refrigerating apparatus including an insulated compartment to be kept cool, a closed refrigerating system associated with said compartment comprising an evaporating means in heat exchange relation with air within the compartment and a refrigerant liquefying and circulating means outside of the compartment. means dependent solely upon the temperature of the refrigerant evaporating means and providing the main control for normally starting the operation of the circulating means at a predetermined high evaporator temperature and normally stopping the operation of the circulating means at a predetermined low evaporator temperature, and means disposed within said compartment out of intimate thermal contact with said evaporatlng means and acting directly upon said temperature dependent main control means ior changing one oi the temperature limits at which same is responsive in response to/the temperature of ambient air in said compartment.

4. Relrigerating apparatus including an insulated compartment to be kept cool. a closed refrigeratlng system associated with said compartment comprising an evaporating means in heat exchange relation with air within the compartment and a refrigerant liquefying and circulating meansjoutslde of the compartment, means dependent solely upon the temperature of the .refrigerant evaporating means and providing the main control for normally starting the operation of the circulating means at a predetermined high evaporator temperature and normally stopping the operation of the circulating means at a predetermined low evaporator temperature, and means disposed within said compartment out oi intimate thermal contact with said evaporating means and acting directly upon said temperature dependentmain control means fior preventing operation of said circulating means and now o! refrigerant through said evaporating means in response to a low temperature-ot ambient iluid in said compartment. Y

' ALBERT O. GROOHB. 

